CN117854805A - Insulated wire - Google Patents

Insulated wire Download PDF

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Publication number
CN117854805A
CN117854805A CN202310844839.2A CN202310844839A CN117854805A CN 117854805 A CN117854805 A CN 117854805A CN 202310844839 A CN202310844839 A CN 202310844839A CN 117854805 A CN117854805 A CN 117854805A
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CN
China
Prior art keywords
insulating film
conductor
insulated wire
area ratio
voids
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Pending
Application number
CN202310844839.2A
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Chinese (zh)
Inventor
牛渡刚真
安藤郁美
西甫
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Bomeilicheng Co ltd
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Bomeilicheng Co ltd
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Publication of CN117854805A publication Critical patent/CN117854805A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
    • H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
    • H01B3/307—Other macromolecular compounds
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B7/00—Insulated conductors or cables characterised by their form
    • H01B7/02—Disposition of insulation
    • H01B7/0233—Cables with a predominant gas dielectric
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B7/00—Insulated conductors or cables characterised by their form
    • H01B7/02—Disposition of insulation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
    • H01B13/06—Insulating conductors or cables
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
    • H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
    • H01B3/303—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups H01B3/38 or H01B3/302
    • H01B3/306—Polyimides or polyesterimides

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  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Organic Insulating Materials (AREA)
  • Insulated Conductors (AREA)

Abstract

The invention provides an insulated wire, which can inhibit the adhesiveness between an insulating film containing a void and a conductor from being reduced. The insulated wire includes a conductor having a long shape and an insulating film including a hollow hole and covering the conductor. The opening area ratio SR measured by the following method is 20% or less. The method for measuring the opening area ratio SR comprises the following steps: the insulating film is peeled off from the conductor, an SEM image showing an interface on the conductor side in the insulating film after peeling is obtained, an area S1 of an observation area as at least a part of the SEM image and an area S2 of a portion of the void opening in the observation area are calculated, and the opening area ratio SR is calculated by the following formula (1). Formula (1): sr= (S2/S1) ×100.

Description

Insulated wire
Technical Field
The present disclosure relates to insulated wires.
Background
An insulated wire such as an enamel wire is provided with a conductor and an insulating film. The insulating film is preferably PDIV (Partial Discharge Inception Voltage) high. PDIV is the partial discharge initiation voltage. As a method for increasing the PDIV of the insulating film, there is a method of providing voids in the insulating film. Patent document 1 discloses a technique for providing voids in an insulating film.
Prior art literature
Patent literature
Patent document 1: WO2016/072425
Disclosure of Invention
Problems to be solved by the invention
By providing the insulating film with the voids, a large number of portions where the voids open may be generated at the interface on the conductor side of the insulating film. In this case, the contact area between the insulating film and the conductor becomes small, and thus the adhesion between the insulating film and the conductor is reduced. In one aspect of the present disclosure, it is preferable to provide an insulated wire and a method for manufacturing the insulated wire, which can suppress a decrease in adhesion between an insulating film including voids and a conductor.
Means for solving the problems
One aspect of the present disclosure is an insulated wire including a conductor having an elongated shape and an insulating film including a void and covering the conductor. The opening area ratio SR measured by the following method is 20% or less.
The method for measuring the aperture area ratio SR comprises the following steps: the insulating film is peeled off from the conductor, an SEM image showing an interface on the conductor side in the insulating film after peeling is obtained, and an area S1 of an observation area as at least a part of the SEM image and an area S2 of a portion of the void opening in the observation area are calculated, and the opening area ratio SR is calculated by the following expression (1).
(1) SR= (S2/S1) ×100
The insulated wire as one aspect of the present disclosure can suppress a decrease in adhesion between an insulating film including voids and a conductor.
Drawings
Fig. 1 is a sectional view showing the structure of an insulated wire.
Fig. 2 is an explanatory diagram showing the configuration of the apparatus used in the peeling test.
Fig. 3 is a cross-sectional view showing the form of the test body with a part of the insulating film removed.
Fig. 4 is an SEM image showing the interface on the conductor side in the insulating film after peeling.
Symbol description
1 … insulated wire, 3 … conductor, 5 … insulating film, 7 … hole, 10T … test body, 100 … test device, 110A, 110B … grip, 120 … rotation mechanism.
Detailed Description
Exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings.
1. Construction of insulated wire 1
As shown in fig. 1, an insulated wire 1 of the present disclosure includes a conductor 3 and an insulating film 5. The conductor 3 has an elongated shape. The cross-sectional shape of the conductor 3 in the cross-section orthogonal to the axial direction of the conductor 3 is not particularly limited. The cross-sectional shape of the conductor 3 is, for example, circular or rectangular.
The material of the conductor 3 is, for example, a metallic material commonly used as a material of an electric wire. Examples of the metal material include copper, copper-containing alloys, aluminum-containing alloys, and the like. Examples of copper include low-oxygen copper having an oxygen content of 30ppm or less, oxygen-free copper, and the like. The diameter of the conductor 3 is preferably 0.4mm or more and 3.0mm or less.
When the cross-sectional shape of the conductor 3 is rectangular, for example, the size in the direction along the major axis of the rectangle (i.e., the width direction) is preferably 1.0mm or more and 5.0mm or less, and the size in the direction along the minor axis of the rectangle (i.e., the thickness direction) is preferably 0.5mm or more and 3.0mm or less.
The insulating film 5 covers the conductor 3. The insulating film 5 is located on the outer peripheral side of the conductor 3. The material of the insulating film 5 is, for example, a material having insulating properties and thermosetting properties. Examples of the material of the insulating film 5 include a resin. Examples of the resin include polyimide. Examples of the polyimide include wholly aromatic polyimide and the like. Examples of the material of the insulating film 5 include a material obtained by polymerizing a diamine or an acid dianhydride, which is an organosilicon monomer, in which at least a part of the main chain is composed of siloxane bonds (-si—o—si-).
The thickness of the insulating film 5 is, for example, 10 μm or more and 200 μm or less. The insulating film 5 has a structure in which a plurality of insulating layers are laminated, for example. The number of the insulating layers to be stacked is, for example, 3 to 60.
As shown in fig. 1, the insulating film 5 has voids 7. The insulating film 5 includes, for example, a plurality of voids 7. For example, the plurality of voids 7 are dispersed in the insulating film 5.
The hollow 7 is a space containing a gas therein. Examples of the gas include air and a gas generated by decomposing a thermally decomposable polymer described later. The diameter of the void 7 is preferably 2 μm or less. In the case where the shape of the void 7 is spherical, the diameter of the void 7 refers to the diameter of the sphere. In the case where the shape of the hollow 7 is a rotational ellipsoid, the diameter of the hollow 7 refers to the diameter along the long axis of the rotational ellipsoid. The rotational ellipsoid means a solid body obtained by rotating an ellipse around its major axis. When the shape of the void 7 is another three-dimensional shape, the diameter of the void 7 is the maximum value of the lengths of the voids 7 measured in any direction.
The diameter of the void 7 refers to the diameter of an individual one of the voids 7. The diameter of the space created by the connection of the plurality of voids 7 during the formation of the insulating film 5 and the diameter of the space created by the connection of the plurality of voids 7 after the formation of the insulating film 5 are not the diameters of the voids 7.
The ratio of the volume of the pores 7 to the total volume of the insulating film 5 was defined as the porosity. The unit of porosity is volume%. The porosity is a value calculated by the following formula (a).
Porosity (volume%) = ((ρ1- ρ2)/ρ1) ×100 of (a)
ρ1 is the specific gravity of an insulating film made of the same material as the insulating film 5 to be measured of the porosity, but having no pores. ρ2 is the specific gravity of the insulating film 5 to be measured as the porosity.
The method for obtaining ρ1 is as follows. An insulated wire was prepared which was substantially the same as the insulated wire 1 to be measured but which had no voids in the insulating film. A portion having a length of 1m was cut out from the insulated wire to obtain a measurement sample. The weight W1a of the insulated wire and the specific gravity ρ1a of the insulated wire were calculated by immersing the insulated wire in ethanol. Next, the insulating film is removed from the insulated wire, and a conductor is obtained. Next, the conductor was immersed in ethanol, and the weight W1b of the conductor and the specific gravity ρ1b of the conductor were calculated. Next, W1b is subtracted from W1a, and the weight W1c of the insulating film is calculated. Next, the specific gravity ρ1 of the insulating film is calculated by the following formula (B).
Formula (B) ρ1=w1c/(w1a/ρ1a-W1B/ρ1b)
The method for obtaining ρ2 is as follows. A portion having a length of 1m was cut out from the insulated wire 1 as a measurement object to be used as a measurement sample. The insulated wire 1 was immersed in ethanol, and the weight W2a of the insulated wire 1 and the specific gravity ρ2a of the insulated wire 1 were calculated. Next, the insulating film 5 is removed from the insulated wire 1 to obtain the conductor 3. Next, the conductor 3 is immersed in ethanol, and the weight W2b of the conductor 3 and the specific gravity ρ2b of the conductor 3 are calculated. Next, W2b is subtracted from W2a, and the weight W2c of the insulating film 5 is calculated. Next, the specific gravity ρ2 of the insulating film 5 is calculated by the following formula (C).
Formula (C) ρ2=w2c/(w2a/ρ2a-w2b/ρ2b)
The porosity is preferably 1% by volume or more and 30% by volume or less, more preferably 4% by volume or more and 20% by volume or less. When the porosity is 1% by volume or more, the relative dielectric constant of the insulating film 5 is lower. When the porosity is 4% by volume or more, the relative dielectric constant of the insulating film 5 is particularly low. When the porosity is 30% by volume or less, the strength of the insulating film 5 can be suppressed from decreasing, and thus crushing, cracking, and the like of the insulating film 5 are less likely to occur at the time of performing coil forming processing. When the porosity is 20% by volume or less, the effect is more remarkable.
The insulating film 5 may contain hollow fine particles, for example. Hollow particles are particles having voids. For example, at least a part or all of the hollow holes 7 provided in the insulating film 5 may be formed of hollow fine particles.
The opening area ratio SR is a value measured by the following method. Using a cutter, a notch is formed at the interface between the insulating film 5 and the conductor 3, and the insulating film 5 is peeled off from the conductor 3. SEM images showing the interface on the conductor 3 side in the insulating film 5 after peeling were obtained. An example of an SEM image is shown in fig. 4. The SEM image shown in fig. 4 is an SEM image obtained in example 1 described later. When SEM images were obtained, the kenji VE series was used as an electron microscope. The acceleration voltage of the electron microscope was 15kV. The magnification of the SEM image was 5000 times.
An area S1 of an observation region, which is at least a part of the SEM image, and an area S2 of a portion of the observation region where the void 7 is open are calculated. The opening area ratio SR is calculated according to the following equation (1). The unit of the opening area ratio SR is%.
(1) SR= (S2/S1) ×100
Area S1 was 420. Mu.m 2 . The method of calculating the area S2 is as follows. First, the brightness of each pixel of the SEM image is 2-valued. That is, when the luminance exceeds the threshold value in any pixel, the pixel is set to be white. When the luminance of any pixel is smaller than the threshold value, the pixel is set to be a black pixel. The threshold is appropriately adjusted in such a manner that voids can be appropriately identified. That is, the threshold value is adjusted so that the portion where the hole is opened becomes a black pixel and the other portion becomes a white pixel. In addition, the hole was bordered and set as a hole, which was not recognized by the 2-valued calculation.
In the SEM image after 2-valued, the area of the portion occupied by the black pixel is calculated. The area of the portion occupied by the black pixel is set to S2. Since the portion of the hole 7 that is open has a lower brightness than other portions, the portion of the hole 7 that is occupied by the black pixel in the SEM image after 2-valued is the portion of the hole.
In the insulated wire 1 of the present disclosure, the opening area ratio SR is 20% or less. By setting the opening area ratio SR to 20% or less, the contact area between the conductor 3 and the insulating film 5 is large, and the adhesion between the conductor 3 and the insulating film 5 is high. The opening area ratio SR is preferably 15% or less, more preferably 1% or less. When the opening area ratio SR is 15% or less, the adhesion between the conductor 3 and the insulating film 5 is higher. When the opening area ratio SR is 1% or less, the adhesion between the conductor 3 and the insulating film 5 is particularly high.
The opening area ratio SR is preferably 0.01% or more, more preferably 0.02% or more. When the opening area ratio SR is 0.01% or more, the relative dielectric constant of the insulating film 5 is lower. When the opening area ratio SR is 0.02% or more, the relative dielectric constant of the insulating film 5 is particularly low.
The insulated wire 1 includes, for example, an enameled wire. Enamelled wires are used, for example, for windings of motors. Examples of the motor include a drive motor of an electric vehicle. Examples of the Electric Vehicle include a hybrid Electric Vehicle (HEV: hybrid Electric Vehicle), an Electric Vehicle (EV: electric Vehicle), and a Plug-in hybrid Electric Vehicle (PHEV: plug-in Hybrid Electric Vehicle).
2. Method for manufacturing insulated wire 1
The insulated wire 1 of the present disclosure can be manufactured by, for example, the following method.
(2-1) preparation of coating
A coating material for forming the insulating film 5 is prepared. The paint contains a first component that is a material of the insulating film 5 (except for the voids 7), a second component that is a component for forming the voids 7, and a solvent. That is, the hollow 7 in the insulated wire 1 is derived from a second component described later.
Examples of the first component include thermosetting resins. Examples of the thermosetting resin include polyimide. Examples of the polyimide include wholly aromatic polyimide composed of diamine and tetracarboxylic dianhydride.
Wholly aromatic polyimide contains 4,4' -diaminodiphenyl ether (ODA) as an essential diamine. The wholly aromatic polyimide may contain 1, 4-bis (4-aminophenoxy) benzene (TPE-Q), 1, 3-bis (4-aminophenoxy) benzene (TPE-R), 1, 3-bis (3-aminophenoxy) benzene (APB), 4' -bis (4-aminophenoxy) biphenyl, or the like as a diamine other than ODA.
In addition, the wholly aromatic polyimide contains pyromellitic dianhydride (PMDA) as an essential tetracarboxylic dianhydride. The wholly aromatic polyimide may contain, as tetracarboxylic dianhydride other than PMDA, 3', 4' -Benzophenone Tetracarboxylic Dianhydride (BTDA), 3',4,4' -diphenylsulfone tetracarboxylic dianhydride (DSDA), 4 '-Oxydiphthalic Dianhydride (ODPA), 4' - (2, 2-hexafluoroisopropylidene) diphthalic anhydride (6 FDA), 3', 4' -biphenyl tetracarboxylic dianhydride (BPDA), and the like.
Examples of the first component include a material obtained by polymerizing a diamine or an acid dianhydride, which is an organosilicon monomer having a siloxane bond (-si—o—si-) at least in part of the main chain.
Examples of the second component include a pore former, core-shell microparticles, and hollow microparticles. Examples of the void former include a thermally decomposable polymer composed of fine particles or a liquid, a high boiling point solvent, and the like.
Examples of the thermally decomposable polymer composed of fine particles include crosslinked acrylic fine particles and crosslinked polystyrene fine particles. Examples of the thermally decomposable polymer composed of a liquid include a glycol type polypropylene glycol (PPG) having hydroxyl groups at both ends.
Examples of the glycol-type polypropylene glycol include a glycol-type polypropylene glycol (PPG 400) having a molecular weight of 400. When a thermally decomposable polymer composed of a liquid is used as the void former, the second component has better compatibility with the solvent than when a thermally decomposable polymer composed of fine particles is used as the void former, and therefore the opening area ratio SR is easily set to 0%. In the case of using a thermally decomposable polymer composed of a liquid, the thermally decomposable polymer is compatible with the coating material via a solvent. On the other hand, when a thermally decomposable polymer composed of fine particles is used as the thermally decomposable polymer, the thermally decomposable polymer is not compatible with the coating material, and the fine particles of the thermally decomposable polymer are dispersed in the coating material. In the case of a thermally decomposable polymer which is a liquid having excellent compatibility with a paint, the paint is heated to volatilize a solvent, whereby the thermally decomposable polymer and the polyamic acid can be phase-separated. Consider that: by forming the insulating film 5 through such a process, the insulating film 5 can be formed without including the voids 7 (i.e., with an opening area ratio SR of 0%) in the interface with the conductor 3.
In particular, when using a glycol-type polypropylene glycol as the void former, the opening area ratio SR can be set to 0%. As the high boiling point solvent, for example, a high boiling point solvent having a boiling point of 260 ℃ or higher may be used. Examples of the high boiling point solvent having a boiling point of 260℃or higher include oleyl alcohol, 1-tetradecyl alcohol, and 1-dodecanol. In the case of using 1-tetradecanol or 1-dodecanol as the void former among these high boiling point solvents, the aperture ratio SR can be set to 20% or less, and the diameter of the voids 7 formed in the insulating film 5 can be easily increased, so that the content of the void former relative to the paint can be reduced and the void content in the insulating film 5 can be increased.
The core-shell type microparticle comprises a core microparticle and a shell. The shell covers the core particles. The core fine particles are composed of, for example, a fine-particle-shaped thermally decomposable polymer.
When the mass of the first component contained in the paint is set to 100 parts by mass, the mass of the second component contained in the paint is preferably 10 parts by mass or more and 60 parts by mass or less. The paint corresponds to the material of the insulating film 5.
Examples of the solvent contained in the paint include N-methyl-2-pyrrolidone (NMP) and dimethylacetamide (DMAc).
(2-2) formation of coating film
A coating material is applied around the conductor 3 to form a coating film. For example, the thickness of the coating film can be adjusted by the following method using a die. The mold has a through hole. First, a coating film thicker than a desired thickness is formed around the conductor 3. Next, the conductor 3 is passed through the through hole. At this time, a part of the outer peripheral portion of the coating film is removed by the mold. As a result, the thickness of the coating film is adjusted.
(2-3) heating
The conductor 3 with the coating film formed thereon was placed in a furnace. The temperature in the furnace is, for example, in the range of 300 to 500 ℃. In the furnace, the solvent contained in the coating film was removed. In addition, voids 7 are created in the furnace by the second component. In the case where the second component is a void former, voids 7 are generated due to vaporization of the void former. When the second component is a thermally decomposable polymer, the thermally decomposable polymer is thermally decomposed and gasified, thereby producing voids 7. In the case where the second component is core-shell type particles, the core particles are thermally decomposed and gasified, thereby creating voids 7. When the second component is hollow fine particles, the voids provided in the hollow fine particles become voids 7.
(2-4) repetition of the procedure
By performing the steps (2-1) to (2-3) 1 times, 1 insulating layer was formed. Next, the steps (2-2) to (2-3) are repeated N times to form an insulating film 5 having an insulating layer formed by laminating an (n+1) layer. N is a natural number of 2 to 59 inclusive.
The larger the amount of the second component contained in the paint, the larger the porosity.
3. Effects of the insulated wire 1
(3-1) the insulating film 5 contains voids 7. Therefore, the dielectric constant of the insulating film 5 is low. The opening area ratio SR is 20% or less. Therefore, the conductor 3 has high adhesion to the insulating film 5.
The opening area ratio SR of (3-2) is, for example, 0.01% or more. When the opening area ratio SR is 0.01% or more, the adhesion between the conductor 3 and the insulating film 5 is high, and the relative dielectric constant is also low.
(3-3) the porosity is, for example, 4% by volume or more. When the porosity is 4% by volume or more, the adhesion between the conductor 3 and the insulating film 5 is high, and the relative dielectric constant can be further reduced.
The hollow holes 7 (3-4) are, for example, hollow fine particles contained in the insulating film 5. In this case, the dielectric constant of the insulating film 5 is lower.
The method for manufacturing the insulated wire 1 of (3-5) includes, for example, the steps of: the coating material is blended with a thermally decomposable polymer or core-shell type particles to thermally decompose the core particles contained in the thermally decomposable polymer or core-shell type particles, thereby forming the voids 7. In this case, the opening area ratio SR can be further reduced.
4. Examples
(4-1) manufacture of insulated wire 1
The insulated wires 1 of examples 1 to 4 and comparative example 1 were manufactured by the method described in the above "method of manufacturing insulated wire 1" section. The composition of the coating material for forming the insulating film 5 is shown in table 1. The blending amount of the coating components in table 1 is in parts by mass. The "resin" in table 1 corresponds to the first component. The "polyimide" in table 1 specifically refers to a wholly aromatic polyimide. The monomer constituting the wholly aromatic polyimide is a monomer containing PMDA and ODA. The "thermally decomposable polymer" in table 1 refers to crosslinked acrylic microparticles. The "high boiling point solvent" in table 1 is specifically oleyl alcohol. In examples 1 to 2 and comparative examples 1 and 3 to 4, the porosity and the opening area ratio SR were changed by adjusting the speed at which the insulating layer constituting the insulating film 5 was formed.
TABLE 1
Examples 1 to 4 and comparative example 1 are common to the following. The material of the conductor 3 is annealed copper. The diameter of the conductor 3 is about 0.8mm. The thickness of the insulating film 5 was about 35. Mu.m. After the coating material is applied around the conductor 3, heating is performed at a temperature of 350 to 500 ℃, thereby forming an insulating layer. Then, the process is repeated a plurality of times to laminate a plurality of insulating layers, thereby forming the insulating film 5 including the voids 7.
(4-2) measurement of open area ratio SR and porosity
The open area ratio SR and the porosity were measured for examples 1 to 4 and comparative example 1, respectively. Fig. 4 shows SEM photographs used to calculate the opening area ratio SR of example 1. The SEM photograph shown in fig. 4 shows the interface on the conductor 3 side in the insulating film 5 after peeling.
The opening area ratio SR of examples 1 to 4 is smaller than that of comparative example 1. The insulating layers were formed at a slower rate in examples 1 and 2 than in comparative example 1. In addition, the speed at which the insulating layer was formed in example 3 was slower than that at which the insulating layer was formed in example 4. From this, it is assumed that in examples 1 to 2, the temperature rising rate at the interface between the insulating layer and the conductor 3 is higher (that is, the rate of curing the paint is higher) than in comparative example 1, and therefore, at least the formation of voids 7 at the interface on the conductor 3 side in the insulating layer is suppressed, and the opening area ratio SR is reduced.
(4-3) Peel test
Peel tests were performed on examples 1 to 4 and comparative example 1, respectively. The method of the peel test is as follows.
The insulated wire 1 was cut in a cross section orthogonal to the axial direction, and the test body 10T was obtained. The length of the test body 10T in the axial direction was 25cm. Test apparatus 100 shown in fig. 2 was prepared. The test device 100 includes grip portions 110A and 110B. The grip portions 110A and 110B face each other with a space therebetween. The distance between the grip 110A and the grip 110B is 25cm. One end of the test body 10T is gripped by the grip 110A. The other end of the test body 10T is gripped by the grip 110B.
The grip 110A is attached to the rotation mechanism 120. The rotation mechanism 120 can rotate the grip 110A. The rotation of the grip 110A is about the center axis of the test body 10T. The grip 110B is fixed so as not to rotate.
Next, as shown in fig. 3, a part of the insulating film 5 provided in the test body 10T is removed. When the test body 10T is viewed in the axial direction, the range from which the insulating film 5 is removed is 2 positions facing each other across the conductor 3. The range from which the insulating film 5 is removed reaches the opposite end from one end of the test body 10T in the axial direction of the test body 10T. The conductor 3 is exposed at the portion from which the insulating film 5 is removed.
Then, the rotation of the grip 110A is started. The rotation of the grip 110A is continued until the insulating film 5 of the sample 10T is peeled off from the conductor 3. The cumulative rotation number of the grip portion 110A from the start of rotation to the time when the insulating film 5 of the sample 10T is peeled off from the conductor 3 is set to the peeling time rotation number. The greater the number of rotations at the time of peeling, the higher the adhesion between the conductor 3 and the insulating film 5. The measurement results of the number of rotations at peeling are shown in Table 1. The number of rotations at peeling in examples 1 to 4 was greater than that at peeling in comparative example 1. The reason why the number of rotations at the time of peeling was large in examples 1 to 4 is presumed to be that the opening area was smaller than SR, and the adhesion between the conductor 3 and the insulating film 5 was high.
5. Other embodiments
The embodiments of the present disclosure have been described above, but the present disclosure is not limited to the above embodiments and can be implemented by various modifications.
(5-1) the functions of one of the above-described embodiments may be shared by a plurality of components, or the functions of a plurality of components may be exhibited by one component. In addition, a part of the constitution of each of the above embodiments may be omitted. At least a part of the constitution of each of the above embodiments may be added or replaced with the constitution of the other above embodiments.
(5-2) in addition to the insulated wire 1, the present disclosure can be realized in various modes such as a motor having the insulated wire 1 as a constituent element, a method of manufacturing the insulating film 5, and the like.
6. Technical matters disclosed in the present specification
[ item 1] an insulated wire comprising a conductor having an elongated shape and an insulating film that includes voids and covers the conductor, wherein the opening area ratio SR measured by the following method is 20% or less.
The method for measuring the opening area ratio SR comprises the following steps: and peeling the insulating film from the conductor. SEM images showing the interface on the conductor side in the insulating film after peeling were obtained. An area S1 of an observation region, which is at least a part of the SEM image, and an area S2 of a portion of the observation region where the void is open are calculated. The opening area ratio SR is calculated by the following equation (1).
(1) SR= (S2/S1) ×100
[ 2] the insulated wire of item 1, wherein the open area ratio SR is 0.01% or more.
[ 3] the insulated wire according to item 1 or 2, wherein the insulating film has a porosity of 4% by volume or more.
[ 4] the insulated wire according to any one of items 1 to 3, wherein the voids are derived from a thermally decomposable polymer or a high boiling point solvent composed of a liquid.
The insulated wire according to item 5, wherein the thermally decomposable polymer comprising a liquid is a glycol-type polypropylene glycol.
[ 6] the insulated wire of item 4, wherein the high boiling point solvent is oleyl alcohol, 1-tetradecyl alcohol, or 1-dodecanol.

Claims (6)

1. An insulated wire comprising a conductor having a long shape and an insulating film which includes voids and covers the conductor;
an opening area ratio SR of the insulated wire measured by the following method is 20% or less;
the method for measuring the opening area ratio SR comprises the following steps: the insulating film is peeled off from the conductor, an SEM image showing an interface on the conductor side in the insulating film after peeling is obtained, an area S1 of an observation area which is at least a part of the SEM image and an area S2 of a portion of the void opening in the observation area are calculated, and the opening area ratio SR is calculated by the following formula (1);
equation (1) sr= (S2/S1) ×100.
2. The insulated wire of claim 1, wherein the open area ratio SR is 0.01% or more.
3. The insulated wire according to claim 1 or 2, wherein the insulating film has a porosity of 4 vol.% or more.
4. The insulated wire of claim 1, wherein the voids are derived from a thermally decomposable polymer or a high boiling point solvent composed of a liquid.
5. The insulated wire according to claim 4, wherein the thermally decomposable polymer made of a liquid is a glycol-type polypropylene glycol.
6. The insulated wire of claim 4, wherein the high boiling point solvent is oleyl alcohol, 1-tetradecyl alcohol, or 1-dodecanol.
CN202310844839.2A 2022-10-07 2023-07-11 Insulated wire Pending CN117854805A (en)

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KR102136081B1 (en) 2014-11-07 2020-07-21 후루카와 덴키 고교 가부시키가이샤 Insulating wire and rotating electric machine
WO2017073551A1 (en) * 2015-10-28 2017-05-04 住友電気工業株式会社 Insulating electric wire and varnish for forming insulating layers
JP2018067516A (en) * 2016-10-21 2018-04-26 住友電工ウインテック株式会社 Insulated wire, resin varnish, and method of manufacturing insulated wire
WO2018180080A1 (en) * 2017-03-31 2018-10-04 住友電気工業株式会社 Insulated electric cable
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